Reverse-flow vaporizer with single inlet and plural outlets



Dec. 20. 1955 L. D. HOWES REVERSE-FLOW VAPORIZER WITH SING INLET AND PLURAL OUTLETS 3 Sheets-Sheet 1 Filed March 27, 1952 7% w T 1 Z TOHA/LY Dec. 20. 1955 L. D. HOWES REVERSE-F LOW VAPORIZER WITH SINGLE INLET AND PLURAL OUTLETS 3 Sheets-Sheet 2 Filed March 27, 1952 Dec. 20. 1955 L. D. HOWES REVERSE-FLOW VAPORIZER WITH SINGLE INLET AND PLURAL OUTLETS 5 Sheets-Sheet 3 Filed March 27, 1952 R N i U Q lllllllillliillrliil K II.

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nnvnn'sn-rnowvnromznn" 'INLET AND :PLURAL 11min Leslie Dennis Howes, Nobel, Canada,- .assignor to A. V. Roe'Cana'da Liniitd,'Milton, Ontario, Canada, a corporation ApplicationMarch 27, 11952, ;No.'278',943

Claims. (CL ill-$9.71)

This invention relates to aniimproved-form :of vaporizer for combustion systems, particularly rcomhustionsystems for gas turbine engines.

in order to ensure fine ;particulation of :the .fuel injected into a combustion chaniber, :it:is common 'practice to pass the fuel through z-some sort of aducting in which it can be preheated and thus transformed-intothe vapor state. These vaporizers {take many'forms ione of the more eflicient being the tube itypeiinwhich 'a cluster of J-shaped tubes is mounted in thenpstream'iendiof "the flame tube, the fuel'beingrled rintosthe longer aim ofthe J and discharged in the opposite direction. from the up-' stream end of theshorter armzof :therJ; inqa vapor-or semi- "ing the safety of the aircraft andsits crew. Furthermore,

the tubular type of vaporizer'is notwell adapted ior use in an annular combustion chamber, asidistingnishedfrom the tube-type combustion systems formerly more. common in gas turbine engines for aircraft; such tubular Vaporizers do not provide "an even of vaporized fuel in the continuous annular vaporizing space which characterizes the annular combustion chambers.

It is the object of 'thisinvention'to provide a'vaporizer of sturdy construction provided with "adequate vaporiz- .ing surfaces, which is not susceptible to burning out. It is a further object of this'invention 'to provide a vaporizer which is particularly adapted for use "in-annular combustion systems.

The invention will be more "readily understood by. reference to the accompanying description and drawingsof preferred embodirnentsthereof. "In these drawings'which form a part of the specification,

Fig. 1 is a side elevation of a gas turbine engine for aircraft, partially cut away to show a tube-type vaporizing system incorporating a vaporizer constructed according to the invention and installed in one of the combustion chambers of the engine;

Fig. 2 is a perspective view of a combustion chamber and flame tube assembly with a portion of the side walls broken away to show one form of vaporizer according to the invention installed therein;

Fig. 3 is a cross-sectional view, from which irrelevant detail has been omitted for clarity, of an annular combustion chamber fitted with a plurality of Vaporizers of the form shown in Fig. 2; and

Fig. 4 is a fragmentary perspective view of an annu- Unitcd StatesPat-tif lar combustion chamber incorporating a modified form of vaporizer constructed according 'to'the invention and particularly adapted for use in annular combustion systems.

Referring to the drawings, Fig. 1 illustrates a tube- "type combustion chamber 10 of conventional form, having a flame tube 11 supported within the walls of the chamber in spaced relationship thereto. A vaporizing assembly 12, constructed in accordance with the invention, is mounted in the upstream end of the combustion chamher (i. e. the left hand side of the drawing in Fig. l, the term upstream being used herein with reference to the normal mainflow of gas through the combustion chamber 19; i. e. from left to right in the drawings), the assembly comprising a frusto-conically-shaped tube 20, with its downstream end closed to the combustion cham- "ber and its upstream end secured to the mounting plate 14 and side Walls surrounding the tube and formed by a series of hollow flutes 21 extending longitudinally provided by the flutes in conjunction with the tube 20.

The wall of the tube is a dividing Wall between an inlet passage-Within the tube and a plurality of outlet passages provided on the other side of the wall of the flutes 21. A' passage from the inlet passage and leading past the dividing wall into the outlet passages is provided by a series of slots 22 in the downstream end of the wall of the tube 20. Swirl vanes 23 are provided within the tube 20 near its upstream end, in order to ensure even distribution of fuel to the several flutes. A conventional fuel nozzle 12* is mounted so that fuel will be directed in the normal manner into the upstream end of the tube 20 while the upstream ends of the flutes 21 are left open to the combustion chamber. The side Walls 13 of the flutes 21 may be made from flat material as shown, so that the vaporizer has a rectangular cross-section, but the walls may be formed to provide a rounded crosssection 'if desired.

When the combustion system is in operation a mixture of fuel and air is fed into the tube 20 and the mixture is diverted by the downstream flow-reversing end well through the slots 22 and then back through the flutes .21 to be discharged into the combustion chamber in a direction counter to the main flow of gas through the chamber. Since combustion is a continuous process the fuel and air mixture is automatically ignited as it leaves .flame tube 11. The vaporizer assemblies 12 are spaced symmetrically around a section of the flame tube and fuel and air is supplied to them as already described.

A modified form of the invention, more particularly applicable to annular combustion chambers, is illustrated in Fig. 4. In this form the inlet passage is provided by an annular supply duct 24 attached at its upper end to a mounting ring 25, while outlet passages 26 are provided by an annular trough 27 having longitudinally corrugated walls, the trough fitting around the downstream end of the supply duct 24. Each of the walls of the supply duct corresponds to the dividing wall between the inlet and outlet passages which in Fig. 2 is formed by the wall of the tube 20. The corrugations are so formed that the convex wall portions 27 of the trough 27 are spaced from the outer walls 24 of the supply duct to define the outlet passages 26, and the concave wall portions 27 of the trough are secured by "of the convex wall portions (as viewed from outside the vaporizer) on the other side presents to the wall of the supply duct a concave surface and provides a flow reversing conduit in conjunction with the supply duct 24. Similarly, each of the concave wall portions (as viewed from outside) presents to the wall of the supply duct a convex surface. The base27 of the trough 2.7 is spaced from the downstream end 24 of the supply duct 24 to provide a port or flow channel between the two. As before, fuel is admitted to the upstream end of the supply duct 24.

It will be readily understood that a small vaporizer of the type just described could readily be used in a tube were.

type combustion chamber, although it is particularly suitable for annular chambers.

The forms of vaporizer described in the foregoing have the advantage of being simple to manufacture and yet extremely rugged and well able to withstand the high operating temperatures normally encountered. They present a large vaporizing surface to the combustion gases, and yet by reason of their construction they do not have the tendency to burn out and fail structurally. which is common to tube type Vaporizers having the longer transverse flow reversal portions.

It is to be understood that the forms of the invention herewith shown and described are to be taken as preferred examples of the same and that various changes may be made in the shape, size and arrangement of the parts without departing from the spirit of the invention or the scope of the subjoined claims.

What I claim as my invention is:

1. In a combustion chamber for a gas turbine engine, which has walls defining a combustion zone through which a combustible stream of air and fuel is caused to flow, a' liquid fuel vaporizer comprising a flow-reversing conduit mounted in the combustion chamber with its axis of flow in the direction of the longitudinal axis of the combustion chamber, the conduit being generally U- shaped in vertical section with its open end facing upstream and having an end wall across the downstream end and side Walls connected to the end wall, one of the side walls being fluted in the longitudinal direction to provide alternated concave and convex surfaces facing the interior of the conduit, the conduit being divided into an inlet passage and a plurality of outlet passages by a partition extending from the open end of the'conduit between the side walls and adjacent the convex surfaces of the said fluted side walls, the concave surfaces being spaced from the partition to provide in co-operation therewith the outlet passages, a passage near the said end wall between the inlet passage and the outlet passages, the open end of the conduit on theside of the partition remote from the fluted wall providing the inlet passage, and means supporting the conduit within the combustion zone, the conduit being spaced from the wall defining the said zone to allow free flow of air around the conduit. 2. A liquid fuel vaporizer for a gas turbine engine combustion chamber having walls defining a combustion zone," comprising an annular fuel supply duct'defined by radially spaced-apart concentric inner and outer side walls and having its central axis substantially parallel to the axis of the combustion chamber, an annular trough having corrugated radially spaced-apart concentric inner and outer side walls and a closed downstream end and disposed over the; downstream-facing end of the fuel duct, the corrugated walls of thetrough providing alternate concave and convex surfacesfacing and contacting the supplyduct'and the closed sneer the trough being spaced from the downstream end of the supply duct, the concave surfaces providing fuel outlet passages between each wall of the trough'and the adjacent wall of the supply duct, and means supporting the supply ductin the combustion zone with the sidewalls 'of th'educt spaced from the walls defining the said zone.

3. A liquid fuel vaporizer as claimed in claim 2 in which the primary fuel duct is supported in the combustion zone ,by an annularmounting ring secured to the combustion chamber.

T 4. A liquid fuel vaporizer as claimed in claim 2 in which at least some of the convex surfaces of each of the trough walls are secured to the adjacent wall of the primary fuel duct.

5. Ina combustion chamber for gas turbine engines, which has a wall defining a combustion zone through which a combustible'stream of air and fuel is caused to .flow, a liquid-fuel vaporizer comprising allow-reversing conduit havingits longitudinal axis substantially parallel to that of the-combustion chamber, the conduit being openlat one end and having side walls and a flow reversing end wall at the other end connecting the side walls, the conduit including a dividing wall within the side walls, an inlet passage on one side of the dividing wall and a plurality of outlet passages separated from the inlet passage by the dividing wall, the dividing wall extending from the open end of the conduit and providing a passage'near the end wall of the conduit for communication between the inlet passage and each outlet passage past the dividing wall, the open end of the conduit on one side of-the dividing wall providing the inlet of the-conduit and the portions of theopen end of the conduit located on the other side of the dividing wall providing the outlets of the conduit, and means supporting the conduit'within thecombustion zone, the conduit being spaced from the wall defining the said zone to allow free flow of air aroundthe conduit.

References Cited inthe'file of this patent UNITED STATES PATENTS 

